Climate ModelingSpring 2010

Edwin Gerber

Basics Ed Gerber (gerber@cims.nyu.edu)

Lectures, Tuesday 9:30-11:20

office hours Tuesday 2-4 or by appt.

Expectations

Attend Lectures, read background material

Course Project

run and/or analyze a climate model

Investigate a Climate Question (more on that later!)

ResourcesTextbooks

A Climate Modelling Primer (Kendal McGuffie + Ann Henderson-Sellers)

fundamentals of atmospheric modeling (Mark Jacobson)

An Introduction to 3-D Climate Modeling (Warren Washington + Clara Parkinson)

History + Context

An Ocean of Air (Gabrielle Walker)

The Discovery of Global Warming (Spencer Weart)

Where to BeginVilhelm Bjerknes (1904)

If it is true, as every scientist believes, that subsequent atmospheric states develop from the preceding ones according to physical law, then it is apparent that the necessary and sufficient conditions for the rational solution of forecasting problems are the following:

1) A sufficiently accurate knowledge of the state of the atmosphere at the initial time.

2) A sufficiently accurate knowledge of the laws according to which one state of the atmosphere develops from another.

Initial Conditions + External Forcing

Composition of the atmosphere + Ocean + Cryosphere + Land Surface

Forcing trends (natural + Anthropogenic)

Climatology of today

Ocean heat content

Ice, Land Surface (chemistry, biology)

Equations of Climateatmosphere

Heat+Mass (water!!) Transport, Albedo (clouds, Aerosols), Radiation Effects (greenhouse), Chemistry

OceanHeat Transport and Storage, chemical uptake and storage

Cryosphere (ice sheets, glaciers, sea Ice) Albedo, Air-Sea Interactions, Sea Level

Land ProcessesChemistry (carbon uptake), Aerosols, Albedo

A Bit of History

Joseph Fourier1824 paper

world warmer than it ought to be -- Atmosphere

trapping Infrared radiation

A Bit of History

Joseph Blackdiscovered CO2

“fixed Air” in 1754[also discovered

Latent Heat]

A Bit of History

John Tyndall1850s - confirmed

that CO2 (0.04% of atmosphere), water vapor are effective

absorbers of “radiant heat” (that is, infrared light)

A Bit of History

Svante Arrhenius1896

Several Months of Calculations:

cut CO2 in half, H20 adjusts, atmo cools 5 K (he was

trying to understand ice

ages)

A Bit of History

Arvig HögbomCO2 increasing

from anthropogenic actions

Arrhenius redid computations, doubling CO2

raises temp 5 K!

Complications . . .

radiation is complex: C02 absorbtion bands May saturate

Oceans contain 50 times the C02, Could easily soak up all emissions!

Water Vapor Feedback is Key -- What if clouds increase albedo?

To the blackboard to get started . . .